Residential / Commercial Gas
Tankless Water Heaters
TANKLESS HIGH EFFICIENCY
CONDENSING WATER HEATERS
Ultra-Low NOx gas tankless water heaters with condensing technology featuring
an unprecedented 0.95 Energy Factor which lowers operating costs and is
environmentally friendly.
FEATURES:
CONTINUOUS MAXIMUM FLOW
RATES UP TO 10.0 GPM
ENERGY STAR® QUALIFIED
AVAILABLE IN NATURAL GAS OR
PROPANE (LP)
540 MODELS
• Can be used in residential and commercial
applications
• Easy-link up to 4 heaters
• Multi-link up to 20 heaters
INDOOR MODEL
• Includes integrated temperature controls
and advanced diagnostics to simplify
troubleshooting
• Factory-installed power cord
OUTDOOR MODEL
• Includes a wall mount temperature remote
controller and advanced diagnostics to
simplify troubleshooting
DURABLE HEAT EXCHANGER:
• Primary heat exchanger is constructed of
a commercial-grade copper that is more
resilient to erosion. Copper is 25x better
at heat transfer than stainless steel thus
stabilizing outgoing water temperatures
quicker.
• Secondary Heat Exchanger is made of Type
316L Stainless Steel to protect against
corrosion.
COMMON VENT UP TO 8 UNITS
SAFETY FEATURES:
• Air-Fuel Ratio (AFR) Sensor
• Exhaust & Water Temperature Safety
Control
• Overheat Cut-Off Fuse
INTERNAL FREEZE PROTECTION
SYSTEM
POWER DIRECT VENT DESIGN
• Category III or IV venting can be used
• Exhaust, 3” PVC Venting up to 70 Feet or
4” PVC Venting up to 100 Feet
• Provides flexible venting with PVC, CPVC,
or ABS Pipe for Intake and Exhaust (solid
core only). Canadian Installations Require
ULCS636 Listed PVC or CPVC Pipe for
Venting.
ACCESSORIES
• Pipe Cover
• Neutralizer Kit
• Isolation Valve Kits
• Concentric Termination
• Product Preservers® Anti-Scale System
• Multi-Unit Controller (540 Model Only)
• Commercial Remote Temperature Control
(540 Model Only)
WARRANTY
• 15-year limited warranty on heat exchanger
in residential applications
• 6-year limited warranty on heat exchanger
in commercial applications
• 5-year warranty on all parts
INDOOR MODELS
ATI-240, ATI-340, ATI-540
OUTDOOR MODELS
ATO-240, ATO-340, ATO-540
COMPLIES WITH LEAD FREE
STANDARDS
©September 2016 A. O. Smith Corporation. All Rights Reserved
www.hotwater.com | 800-527-1953 Toll-Free USA | A. O. Smith Corporation | 500 Tennessee Waltz Parkway | Ashland City, TN 37015
540 models
only
ANSI Z21.10.3 CSA 4.3
Page 1 of 6
AOSRG46835
TANKLESS HIGH EFFICIENCY CONDENSING MODELS
Residential / Commercial Gas
Tankless Water Heaters
Model
Number
Indoor Models
ATI-240H-N Natural 15,000 160,000 4.0 10.5 0.95 6.6 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATI-240H-P Propane 13,000 160,000 8.0 14.0 0.95 6.6 3/4” NPT 3/4” NPT 23-5/9 17-3/4 11-1/4 58
ATI-340H-N Natural 15,000 180,000 4.0 10.5 0.95 8 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATI-340H-P Propane 13,000 180,000 8.0 14.0 0.95 8 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATI-540H-N Natural 15,000 199,000 4.0 10.5 0.95 10 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 59
ATI-540H-P Propane 13,000 199,000 8.0 14.0 0.95 10 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 59
Outdoor Models
ATO-240H-N Natural 15,000 160,000 4.0 10.5 0.95 6.6 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-240H-P Propane 13,000 160,000 8.0 14.0 0.95 6.6 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-340H-N Natural 15,000 180,000 4.0 10.5 0.95 8 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-340H-P Propane 13,000 180,000 8.0 14.0 0.95 8 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 58
ATO-540H-N Natural 15,000 199,000 4.0 10.5 0.95 10 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 59
ATO-540H-P Propane 13,000 199,000 8.0 14.0 0.95 10 3/4” NPT 3/4” NPT 23-5/8 17-3/4 11-1/4 59
15-150 PSI Water Pressure. 40 PSI or above recommended for maximum flow.
*Current numbers based on factory testing; 0.5 GPM for activation; 0.4 GPM required for continuous fire after initial ignition.
Indoor models are certified from sea level to 10,100 ft. elevations. Outdoor models are certified from sea level to 6,000 ft. elevation.
Type
Gas Consumption Input Inlet Gas Pressure
Minimum
BTU/H
Maximum
BTU/H
Minimum
in. W.C.
Maximum
in. W.C.
Energy
Factor
(EF)
Maximum
GPM*
Hot/Cold
Connections
Gas
Connection
Dimensions in Inches
Height Width Depth
Unit
Weight
(lbs)
Page 2 of 6
AOSRG46835
7-7/8" (199 mm)
GAS 5-1/8" (131 mm)
OLD 6-3/4" (172 mm)
T 5-1/2" (140 mm)
5-3/4" (147 mm)
C 6-7/8" (174 mm)
4" (102 mm)
INDOOR MODEL
Female
24-7/8" (631 mm)
23-5/8" (600 mm)
17-3/4" (450 mm)
7" (180 mm)
6-1/4" (159mm)
Residential / Commercial Gas
Tankless Water Heaters
INDOOR MODEL
4" (101 mm)
4" (102 mm)
Female
11-1/4" (285 mm)
22-1/2" (570 mm)
5-3/4" (147 mm)
Intake
2-5/8" (68 mm)
2-5/8" (65 mm)
Exhaust
10-3/4" (272mm)
HOT 4-3/4" (120 mm)
Drain port
6-3/4" (170 mm)
HOT 4-3/4" (120 mm)
120 VA
HO
COLD 5/8" (17 mm)
120 VAC 3" (77 mm)
GAS 5-3/4" (147 mm)
Condens ate drain port
7-1/2" (189 mm)
Condens ate drain port
7-1/2" (189 mm)
GAS 5-7/8" (147 mm)
120 VAC 3" (77 mm)
COLD 5/8" (17 mm)
C
1/2 (13 mm)
GAS 5-1/8" (131 mm)
HOT 5-1/2" (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)
120 VAC 6-7/8" (174 mm)
Condens ate drain port
7-7/8" (199 mm)
17-5/8" (448 mm)
Condensate drain port
6-1/4" (159 mm)
Page 3 of 6
AOSRG46835
T 5-1/2" (140 mm)
GAS 5-1/8" (131 mm)
OLD 6-3/4" (172 mm)
7-7/8" (199 mm)
24-7/8" (631 mm)
OUTDOOR MODEL
23-5/8" (600 mm)
17-3/4" (450 mm)
7" (180 mm)
Residential / Commercial Gas
Tankless Water Heaters
OUTDOOR MODEL
4-1/2" (114 mm)
1-1/2" (37 mm)
3-5/8" (92 mm)
11-1/4" (285 mm)
11" (281 mm)
22-1/2" (570 mm)
HOT 4-3/4" (120 mm)
120 VAC 6-1/4" (159 mm)
Drain port
6-3/4" (170 mm)
HOT 4-3/4" (120 mm)
HO
120 VAC 3" (77 mm)
120 VAC
6-1/4" (159 mm)
COLD 5/8" (17 mm)
GAS 5-3/4" (147 mm)
Condens ate drain port
7-1/2" (189 mm)
Condens ate drain port
7-1/2" (189 mm)
COLD 5/8" (17 mm)
C
10-3/4" (272 mm)
1/2" (13 mm)
120 VAC 3" (77 mm)
GAS (131 mm)
HOT (140 mm)
Drain port 6" (152 mm)
COLD 6-3/4" (172 mm)
Condens ate drain port
7-7/8" (199 mm)
17-5/8" (448 mm)
Condensate drain port
Page 4 of 6
AOSRG46835
Residential / Commercial Gas
FLOW RATE vs TEMPERATURE RISE
01
PRESSURE LOSS
Set temperature 130˚F (55˚C) or higher
Tankless Water Heaters
FLOW RATE vs TEMPERATURE RISE
240H
11.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
Flow Rate (GPM)
3.0
2.0
1.0
0.0
Flow Rate vs. Temperature Rise Flow Rate vs. Temperature Rise
020406080100
Temperature Rise (°F)
11.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
Flow Rate (GPM)
3.0
2.0
1.0
0.0
11.0
10.0
9.0
8.0
7.0
6.0
5.0
4.0
Flow Rate (GPM)
3.0
2.0
1.0
0.0
02040608
Temperature Rise (°F)
540H
Flow Rate vs. Temperature Rise
020406080100 120140
Temperature Rise (°F)
Temperature Rise (˚F)
Set temperature 125˚F (52˚C) or lower
Set temperature 130˚F (55˚C) or
higher
340H
00
PRESSURE LOSS
240H
50
45
40
35
30
25
20
Pressure Loss (psi)
15
10
5
0
0.01.0 2.03.0 4.05.0 6.07.0 8.09.0 10.0
Pressure Loss
Flow Rate (GPM)
50
45
40
35
30
25
20
Pressure Loss (psi)
15
10
5
0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11 .0 12.0
120
100
80
60
40
20
0
50
45
40
35
30
25
20
Head (Feet)
Pressure Loss (psi)
15
10
5
0
0.01.0 2.03.0 4.05.0 6.07.0 8.09.0 10.0
540H
Pressure Loss
Flow rate (GPM)
Flow Rate (GPM)
Set temperature 125˚F (52˚C) or lower
340H
Pressure Loss
Flow Rate (GPM)
120
100
80
60
Head (Feet)
40
20
0
120
100
80
60
Head (Feet)
40
20
0
Page 5 of 6
AOSRG46835
Residential / Commercial Gas
Tankless Water Heaters
SUGGESTED SPECIFICATION FOR ATI-540H OR ATO-540H
The fully modulating, on-demand, condensing gas fired tankless water heater(s) shall be A. O. Smith Tankless Water Heater model ATI-540H or
ATO-540H, having a maximum input rating of 199,000 Btu/h and available in NG or LP. The heater shall have ¾ in. male NPT water and gas
connections. The inlet gas supply pressures shall be 4.0 in. WC (min.) up to 10.5 in. WC (max.) for NG and 8.0 in. WC (min.) up to 14 in. WC
(max.) for LP. The indoor heater(s) shall incorporate an integrated temperature controller that will provide diagnostic information, fault history,
and heater set temperature. The outdoor heater shall be factory supplied with a temperature remote, 9009069005, that can be installed up
to 400 ft. from the heater using 20 gauge (minimum) control wire. The temperature remote shall provide diagnostic information, fault history,
and heater set temperature. The heater shall operate using 120 V / 60 Hz power source. The indoor heater will incorporate a factory installed
power cord.
The indoor heater shall be vented with 3” or 4” diameter schedule 40 PVC (solid core), CPVC, ABS, polypropylene or category IV vent pipe
with a length not to exceed 70 ft. (equivalent) for 3” vent or 100 ft. (equivalent) for 4” vent, terminating horizontally or vertically. The intake
pipe may use material such as PVC, CPVC, ABS, aluminum, or Category IV pipe and cannot exceed 70 ft. (equivalent) for 3” vent or 100 ft.
(equivalent) for 4” vent. The indoor heater shall be able to be common vented with schedule 40 PVC pipe or approved polypropylene vent
with a length not to exceed 100 ft. (equivalent) using up to 10 in. pipe. Proper sizing is provided in the heater’s installation manual. The
outdoor heater(s) shall be constructed with an integral exhaust vent on the front of the heater.
The water heater shall use a commercial grade copper alloy, fin tube primary heat exchanger with quick release brass or bronze waterways.
The secondary heat exchanger shall be constructed from stainless steel 316L. The heater shall be controlled by an onboard solid-state printed
circuit board which uses the following factory installed components: thermistors to monitor inlet & outlet water temperature and exhaust
temperature; a flow sensor to measure flow rate; a flame sensor to monitor combustion; an air-fuel ratio rod to measure and adjust operation
in order to maintain optimal combustion efficiency. The heater also consists of inline fusing and surge absorbers for electrical surge protection,
an electronic spark igniter, aluminized stainless steel burners, hi-limit temperature switches to monitor water and exhaust temperatures,
modulating gas valve, an overheat cutoff fuse, ceramic heating blocks to protect the heat exchanger and water piping. The indoor heater shall
incorporate auto-fire system for additional freeze protection. The indoor model shall include an exhaust temperature monitoring system using
an exhaust thermistor and automatic hi-limit switch to maintain safe exhaust temperatures for sch. 40 PVC. The heater shall have a built-in
condensate trap for the secondary heat exchanger.
The heater can manifold to Easy-Link up to 4 heaters to provide additional capacity. The Easy-Link controls shall be built onto the onboard
solid-state printed circuit board and does not require external controls. The linking control wire shall be supplied with the heater. The heaters
can use a Multi-Unit controller, 9008300005, to manifold 5-20 heaters. The Easy-Link and Multi-Unit Controller shall modulate the system
for the most efficient performance. The Easy-Link and Multi-Unit Controller shall rotate the priority heater every 12 hours of operation time or
100 starts for balanced duty/cycle operation.
The heater shall be design certified by CSA according to ANSI Z21.10.3, approved for sale in the United States, ENERGY STAR® qualified, has
a minimum energy factor of 0.95, meets the energy efficiency requirements of the U. S. Department of Energy and ASHRAE 90.1, complies
with SCAQMD Rule 1146.2 and other air quality districts with similar requirements for low NOx emissions of 14 ng/J or 20 ppm, and shall be
certified by NSF to NSF/ANSI 5 Standard.
For technical information call 800-527-1953. A. O. Smith Corporation reserves the right to make product changes or improvements without prior notice.
©September 2016 A. O. Smith Corporation. All Rights Reserved
www.hotwater.com | 800-527-1953 Toll-Free USA
Page 6 of 6
AOSRG46835
Loading...